Concept:
Formal charge on an atom is calculated by:
\[
\text{Formal Charge}=
\text{Valence electrons}
-\text{Non-bonding electrons}
-\frac{\text{Bonding electrons{2}
\]
It helps determine charge distribution in a Lewis structure.
Step 1: Identify the atom
We need formal charge on carbon atom in the structure:
\[
O=C=O
\]
(Carbon dioxide)
Step 2: Valence electrons of carbon
Carbon belongs to Group 14.
\[
\text{Valence electrons of C}=4
\]
Step 3: Non-bonding electrons on carbon
Carbon forms two double bonds and has no lone pair.
\[
\text{Non-bonding electrons}=0
\]
Step 4: Bonding electrons around carbon
Carbon is double bonded with two oxygen atoms.
Each double bond contains $4$ electrons.
So total bonding electrons around carbon:
\[
4+4=8
\]
Step 5: Apply formula
\[
\text{Formal Charge on C}
=4-0-\frac{8}{2}
\]
\[
=4-4
\]
\[
=0
\]
Step 6: Final Answer
The formal charge on carbon atom is:
\[
\boxed{0}
\]
Quick Tip:
In the most stable Lewis structure of $CO_2$, both oxygen and carbon have formal charge zero.
